在django模板中显示ManyToManyField

from django.db import models

class Article(models.Model):
    title = models.CharField(max_length=100)
    tags = models.ManyToManyField('Tag')

from django.shortcuts import render
from .models import Article

def article_detail(request, article_id):
    article = Article.objects.get(id=article_id)
    return render(request, 'article_detail.html', {'article': article})

<h1>{{ article.title }}</h1>
<h2>Tags:</h2>
<ul>
  {% for tag in article.tags.all %}
    <li>{{ tag }}</li>
  {% endfor %}
</ul>